class Book {
    constructor(isbn, title, author) {
        this.isbn = isbn;
        this.title = title;
        this.author = author;
    }
    display() {
        return `
        ISBN号:${this.isbn}
        Title: ${this.title}
        Author:${this.author}
        `
    }
}
//作业   返回所有对象上可以调用的方法或属性 attrs
let jsDontKnow = new Book('111', 'aa', 'bb');
const attrs = [...Object.getOwnPropertyNames(jsDontKnow), ...Object.getOwnPropertyNames(Book.prototype)];
console.log(attrs);